require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

ruby_version_is "1.9" do
  describe "StringIO#readpartial" do
    before :each do
      @string = StringIO.new('Stop, look, listen')
    end

    after :each do
      @string.close unless @string.closed?
    end

    it "raises IOError on closed stream" do
      @string.close
      lambda { @string.readpartial(10) }.should raise_error(IOError)
    end

    it "reads at most the specified number of bytes" do

      # buffered read
      @string.read(1).should == 'S'
      # return only specified number, not the whole buffer
      @string.readpartial(1).should == "t"
    end

    it "reads after ungetc with data in the buffer" do
      c = @string.getc
      @string.ungetc(c)
      @string.readpartial(4).should == "Stop"
      @string.readpartial(3).should == ", l"
    end

    it "reads after ungetc without data in the buffer" do
      @string = StringIO.new
      @string.write("f").should == 1
      @string.rewind
      c = @string.getc
      c.should == 'f'
      @string.ungetc(c).should == nil

      @string.readpartial(2).should == "f"
      @string.rewind
      # now, also check that the ungot char is cleared and
      # not returned again
      @string.write("b").should == 1
      @string.rewind
      @string.readpartial(2).should == "b"
    end

    it "discards the existing buffer content upon successful read" do
      buffer = "existing"
      @string.readpartial(11, buffer)
      buffer.should == "Stop, look,"
    end

    it "raises EOFError on EOF" do
      @string.readpartial(18).should == 'Stop, look, listen'
      lambda { @string.readpartial(10) }.should raise_error(EOFError)
    end

    it "discards the existing buffer content upon error" do
      buffer = 'hello'
      @string.readpartial(100)
      lambda { @string.readpartial(1, buffer) }.should raise_error(EOFError)
      buffer.should be_empty
    end

    it "raises IOError if the stream is closed" do
      @string.close
      lambda { @string.readpartial(1) }.should raise_error(IOError)
    end

    it "raises ArgumentError if the negative argument is provided" do
      lambda { @string.readpartial(-1) }.should raise_error(ArgumentError)
    end

    it "immediately returns an empty string if the length argument is 0" do
      @string.readpartial(0).should == ""
    end

  end
end
